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  Campbell, S.J.; Hofmann, M.; Mole, R.A.; Prokes, K.; Wallacher, D.; Wang, J.L.: Magnetic Order in YbMn₂Si₂ - Neutron Scattering Investigation. Journal of the Korean Physical Society 63 (2013), p. 314-319

10.3938/jkps.63.314

Abstract:
Several mechanisms have been proposed to account for the structural and magnetic behaviour of the rare earth intermetallic compound YbMn2Si2 below the transition that occurs around ∼30 K. We have carried out detailed neutron diffraction measurements over the temperature range ∼0.3 - 52 K and confirm both an antiferromagnetic structure with ferromagnetic Mn (001) planes coupled antiferromagnetically along the c-axis above ∼30 K and the absence of ordering of the Yb sublattice down to 0.3 K. The decrease in intensity of the (111) reflection around ∼30 K together with the appearance of satellite reflections of propagation vector k = 001/2 confirm that the magnetic unit cell doubles along the c axis below TN2. The resultant molecular field acting on half of the ions below ∼30 K removes the degeneracy of the Kramers doublets of the Yb3+ ions and accounts for the additional excitations observed below ∼30 K compared with the inelastic neutron scattering above ∼30 K.